The prevention of interference between civilian and government communication and navigation systems is a continuing challenge to operators of wireless systems. This problem becomes even more complex as the ability to “roam” across national boarders is becoming available in an increasing number of commercially available wireless devices and the networks on which they operate.
802.11 is a set of standards created by the Institute of Electrical and Electronics Engineers (IEEE), an international standards-setting group. The standards govern wireless networking transmission methods and have several versions, such as the well-known 802.11a, 802.11b, and 802.11g, which are used to provide wireless connectivity in the home, office, and some commercial establishments.
An amendment to the 802.11 standard, called 802.11h, prevents wireless networks from obstructing radar, Earth Exploration Satellite Service (EESS), and Space Research Service (SRS) transmission. The 802.11h amendment calls for, among other things, Wireless Local Area Networks (WLANs) and other devices to detect the presence of radar activity and to protect them from interference by avoiding operation on their communication channel or reducing transmission power. Although the IEEE 802.11h specification describes the requirement of radar avoidance, the standard does not resolve the issue of how avoidance is to be carried out. The design and implementation of a radar avoidance mechanism is left to the developers of an 802.11 network and/or devices.
Therefore, a need exists to prevent 802.11 stations from transmitting on channels where a radar system may be operating.